js code to remove space between numbers in a string

This is very close to santosh singh answer, but will not replace the space between is and 5.

const regex = /(\d)\s+(?=\d)/g;
const str = `The store is 5 6 7 8`;
const subst = `$1`;

// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);

console.log('Substitution result: ', result);

https://regex101.com/r/nSZfQR/3/

You can try following code snippet.

const regex = /(?!\d) +(?=\d)/g;
const str = `The store is 5 6 7 8`;
const subst = ``;

// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);

console.log('Substitution result: ', result);

Hi You can try this.

var str = "The store is 5 6 7 8"
var regex = /(\d+)/g;
str.split(/[0-9]+/).join("") + str.match(regex).join('')

Hope this will work.

/([0-9]+) ([0-9]+)/ - removes space between digits. But running s.replace replaces only first occurrences. I put in into loop, so it keep deleting all spaces between two digits until there is no more spaces between digits.

prevS = ''; 
while(prevS !== s){
   prevS = s; s = s.replace(/([0-9]+) ([0-9]+)/, '$1$2');
}